Generic types of wheels are used in rail vehicles for local and regional transportation, for streetcars, elevated trains, subway trains, local commuter trains, and metropolitan trains. The wheels for running on rails that are available on the market, all similar rubber-sprung wheels, essentially consist of a wheel body, a clamp ring, individual rubber blocks or one or two rubber rings, and a wheel tire. The general goal of using rubber-sprung wheels is to reduce impact shocks, vibrations, and shaking on the chassis and the coach box. This is achieved by reducing the unsprung masses of the pairs of wheels or portal axles. This is also to have a positive effect on the loads on the rails and on their pavement bed. A reduction of the rolling and squealing noises is achieved through uncoupling by the rubber elements and their damping. An advantage over the classic solid wheel, in which the wheel is made out of steel in one piece, is further that after wear on the wheel, only the wheel tire and possibly the rubber chocks or rubber rings must be changed, whereas with a solid wheel the complete wheel must be replaced. In using this type of wheel, combined shearing and pressure loads occur, which have an effect on the wheel and in particular on the damping action of the wheel. The slope of the arranged elastic dampers relative to the rotation axis determines whether the load of the dampers occurs primarily as a thrust from a radial load during operation or as a combination of thrust and pressure.
For example, compliant or elastic wheels in the form of so-called one- or two-ring wheels are known, in which the elastic connection is achieved between the wheel tire and the two flanges of the wheel body and the clamp ring, respectively, arranged at a lateral distance via one or two rubber rings set up concentrically to the rotation axis of the wheel, or via numerous rubber blocks made of an elastic material arranged circumferentially at a distance from one another with a defined cross-sectional shape. Thereby the rings or blocks often have a substantially rectangular cross-sectional shape. The rubber blocks are thereby made significantly flat and rectangular or with two sloping sides with flat angles. Such rubber-sprung wheels with rubber chocks are subject to high initial stress, and are fixed axially in a positive lock by shoulders on wheel tire, wheel body, and clamp ring. The rubber inlays are here predominantly subject to pressure. These wheels are very stiff and thereby have very low spring or damping qualities.
EP 0 489 455 B1 describes a generic embodiment of a rubber-sprung wheel. Here, the damping means, which are arranged in a U- or V-shaped, ring-shaped intermediate space between wheel body, wheel tire, and clamp ring, are made of a rubber ring, which preferentially forms an obtuse angle of 60° with the wheel axis and is pre-stressed during assembly.
Such wheels are characterized according to the angle setting (15°, 30°, 60° or greater, but ≤90°), by medium to high stiffness, and thereby have low to medium spring or damping qualities. As the angle setting of the rubber rings increases, so does the pressure load in the direction of the thrust load.
Additional generic embodiments are described in U.S. Pat. No. 2,138,506 A and U.S. Pat. No. 2,175,118 A. These wheels are stressed only upon thrust by their rings serving as dampers oriented perpendicular to the rotation axis, and thereby allow relatively high spring deflection. The contact area between elastomer and steel components is provided partially with metal sheets, which are meant to create a positive lock for the transmission of power. When using a vulcanized rubber material, these metal sheets are integrated with the elastic material in a vulcanizing process into a compound component. In addition, a multitude of molded projections on the contact surfaces of these rings have been described. These projections are arranged equally distributed on a circular ring, and are manufactured in the form of sheet-metal pass-throughs.
In addition, another generic embodiment of a wheel is described in EP 0 893 279 B1. In this embodiment, the damping means are formed as two similar rings made of an elastomer material, each of which is frustoconical in shape. Both rings are attached perpendicular to the axis of the wheel and set up symmetrically to a center plane perpendicular to the axis of the wheel, wherein the metallic reinforcements are embedded in each ring and are set up adjacent to the frustoconical inner or outer wall of the ring. Each ring has projections protruding from the frustoconical inner and outer wall of the ring, which projections prevent shifting. Such wheels with annular rings and a corresponding number of projections have the disadvantage that they have multiple alignments between the projections of the rings and the corresponding recesses of the tire, of the wheel body, or of the clamp ring. The required narrow tolerances of the geometry in ring-shaped rubber elements, in particular with metal sheets on the outer sides or in the core, and the projections and their shape and position, increase the expense for manufacturing molds. In the same way, there may be alignment problems in assembly with the adjacent metal parts of the wheel, in which the corresponding recesses also must be manufactured with necessarily exact tolerances in their geometry and their shape and position. Here, one must plan for a certain play in the space in order to allow assembly, which has a negative effect on the direct transmission of force and momentum. In addition, the costs of manufacturing and storing the rings are comparatively high because they are relatively large components. Depending on the wheel diameter, a manufacturer must produce several construction sizes of such rings in order to account for customer wishes. Moreover, the outermost layer of the projections is made of an elastomer material, which in comparison with metal is subject to greater wear. The play in the alignment itself and its enlargement can, due to wear of the outer elastomer layer, lead to or accelerate a possible slip-through of the damping means between the steel components (wheel tire, clamp ring, and wheel body) because of the wearing away of the outer elastomer layer.
Another known embodiment of this type is described in EP 2 357 092 B1. In this embodiment, the damping means are formed as several rubber blocks equally distributed around the circumference of the wheel. The rubber blocks are set up on both sides between the circumferential ridge of the wheel tire and the ring flange of the tire body or the clamp ring. The rubber blocks have the form of ring sectors and run radially perpendicular to the rotation axis of the wheel. Each of the rubber blocks consists of two rubber segments, which are designed either as rubber blocks arranged one above the other in the radial direction and connected to one another via a rubber ridge, or as two separate rubber blocks arranged radially above one another. The rubber segments each have a projection on one side, with which, in the engaged state, they mesh into an assigned recess of the clamp ring or of the ring flange. Such wheels have the disadvantage, in particular, that the radial construction height is relatively great because of the rubber blocks that extend in the radial direction. This is undesirable particularly with low floor vehicles that accommodate the handicapped. In addition, each rubber segment of the rubber blocks has only one projection in each case, so that there is poor acceptance of tangentially running forces or of torsion forces occurring on the rubber segments, in turn leading to more rapid wear and tear of the rubber segments. In particular because the rubber blocks run radially perpendicular to the rotation axis, high combined shear and pressure loads lead to high shearing forces on the rubber blocks, and in particular on the projections of the rubber segments, so that as a result these wear down relatively quickly. In addition, such rubber segments are sensitive to flexing, such as occurs when wheels are operating, so that there may be increased damage due to increased temperature and slippage.
Disadvantageously, the rubber sprung wheels described above have relatively numerous rubber blocks, which during assembly are individually manually positioned, and then during assembly must be secured against being pulled out or falling out. In addition, spring or damping behavior that is not constant may occur when rubber blocks are used because of gaps between the rubber blocks. This inconstant behavior is reinforced by the use of rubber elements, which in the mounted position are not arranged symmetrically to the wheel axis.